1. Field of the Invention
The present invention relates to an electrophotographic photosensitive drum, a process cartridge detachably mountable to a main body of an electrophotographic image forming apparatus, and the electrophotographic image forming apparatus.
An electrophotographic image forming apparatus is an apparatus for forming an image on a recording medium by using an electrophotographic image forming system. For example, such electrophotographic image forming apparatuses include an electrophotographic copying machine, an electrophotographic printer (e.g., a laser beam printer, an LED printer, etc.), a facsimile telegraph, a word processor, etc.
The process cartridge may be a cartridge into which charging means, developing means or cleaning means and an electrophotographic photosensitive drum are integrally incorporated, and which is detachably mountable to the main body of the image forming apparatus. Alternatively, the process cartridge may be a cartridge into which at least one of the charging means, the developing means and the cleaning means, and the electrophotographic photosensitive drum are integrally incorporated, and which is detachably mountable to the main body of the image forming apparatus. Further alternatively, the process cartridge may be a cartridge into which at least the developing means and the electrophotographic photosensitive drum are integrally incorporated, and which is detachably mountable to the apparatus main body.
2. Related Background Art
An electrophotographic image forming apparatus using an electrophotographic image forming process conventionally adopts a process cartridge system in which the electrophotographic photosensitive drum and process means acting on this electrophotographic photosensitive drum are integrally made into a cartridge and this cartridge can be detachably mounted to the main body of the image forming apparatus. In accordance with this process cartridge system, the image forming apparatus can be maintained by a user himself without any service man so that operability can be greatly improved. Therefore, this process cartridge system is widely used in the electrophotographic image forming apparatus.
An electrophotographic image forming apparatus for replenishing toner by a toner replenishing device is also used while the electrophotographic photosensitive drum and a developing device are built in the main body of the image forming apparatus.
In the electrophotographic photosensitive drum (hereinafter referred to as a photosensitive drum) used in such an electrophotographic image forming apparatus, a metallic cylindrical base body made of aluminum, for example, is coated with a photoconductor such as an OPC, and is set to the photosensitive drum, and a gear flange or a flange having a coupling to receive driving force is mounted to an end portion of the photosensitive drum.
A method for adhering the gear flange is conventionally adopted as a method for mounting this gear flange to the photosensitive drum. However, in using such adhesion, it is necessary to strictly control the amount of the adhesive, and the temperature and humidity during adhesion. Further, fitting sizes of the gear flange and the photosensitive drum must be maintained with required accuracy. If the clearance between the gear flange and the photosensitive drum is too large, sufficient adhesive force can not be obtained. If an outer shape of the flange is too large, so that the flange is press fit into the photosensitive drum, the photosensitive drum may be deformed. Further, a curing time is required so as to obtain sufficient adhesive force after an adhesive process.
Therefore, so-called caulking for plastically deforming one portion of the cylinder after the gear flange is inserted into the photosensitive drum, and integrating the cylinder with the gear flange is proposed and executed (e.g., U.S. Pat. No. 5,771,425).
Here, caulking coupling will be explained with reference to FIGS. 25 to 29. FIG. 25 is a side view of the photosensitive drum and the gear flange before they are coupled to each other. FIG. 26 is a partial front view of the gear flange. FIG. 27 is a cross-sectional view of the gear flange and the photosensitive drum when the gear flange is inserted into the photosensitive drum. FIG. 28 is a view explaining a caulking process. FIG. 29 is a perspective view of a photosensitive drum unit after the caulking process.
The caulking process will sequentially be explained. First, a gear flange 2 is inserted into the end of a photosensitive drum 7, which includes a metallic cylinder having a photosensitive layer on its outer circumference. At this time, the position of a caulking hole 2k formed in the gear flange 2 is adjusted such that this position is in phase conformity (registration) with that of a punch 45 of a caulking tool. To facilitate this adjustment, a rib 2m is formed in the gear flange 2 in advance in a position conforming to the caulking hole 2k in a circumferential direction, and a function for detecting the position of the rib 2m is provided in a chucking tool of the gear flange 2 so as to conform the positions of the caulking hole 2k and the punch 45 to each other in phase when inserting the gear flange 2 into the photosensitive drum 7. Next, the punch 45 of the caulking tool is moved in a direction indicated by an arrow of FIG. 28 and the metallic cylinder is cut so as to form a tab which is bent toward an inner side in the conforming position, into the caulking hole 2k, so that a cut bent (tab) portion 7t is formed. The cut bent (tab) portion 7t of the metallic cylinder bites into the gear flange 2 so that the photosensitive drum 7 and the gear flange 2 are integrated with each other. Therefore, high reliability can be secured since dislocation and running idle of the gear flange 2 are prevented.
The present invention is made by further developing the above-mentioned background art.